PassThePopcorn has a similar CAPTCHA-like implementation to the Pexels one you mentioned in your article. It has a repository of movie posters (which I think are user submitted to the movies themselves), one of which is chosen and the user is asked what movie the poster is for. I've always thought of that as an "enjoyable" CAPTCHA.
GazelleGames does that with game covers. Lichess has one where you need to find a checkmate in one move. It's usually pretty easy, but could in theory be frustrating for someone just starting with chess.
I've always thought this is a terrible CAPTCHA, not because it's hard but because one could reasonably write a bot that simply reverse image searches the movie poster and picks the closest response.
